[NET]: skb_trim audit

I found a few more spots where pskb_trim_rcsum could be used but were not.
This patch changes them to use it.

Also, sk_filter can get paged skb data.  Therefore we must use pskb_trim
instead of skb_trim.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -873,10 +873,7 @@ static inline int sk_filter(struct sock *sk, struct sk_buff *skb, int needlock)
 		if (filter) {
 			unsigned int pkt_len = sk_run_filter(skb, filter->insns,
 							     filter->len);
-			if (!pkt_len)
-				err = -EPERM;
-			else
-				skb_trim(skb, pkt_len);
+			err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
 		}
 
 		if (needlock)

net/bridge/br_netfilter.c

@@ -407,12 +407,8 @@ static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 	if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 		if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 			goto inhdr_error;
-		if (pkt_len + sizeof(struct ipv6hdr) < skb->len) {
-			if (__pskb_trim(skb, pkt_len + sizeof(struct ipv6hdr)))
-				goto inhdr_error;
-			if (skb->ip_summed == CHECKSUM_HW)
-				skb->ip_summed = CHECKSUM_NONE;
-		}
+		if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
+			goto inhdr_error;
 	}
 	if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 		goto inhdr_error;
@@ -495,11 +491,7 @@ static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
 	if (skb->len < len || len < 4 * iph->ihl)
 		goto inhdr_error;
 
-	if (skb->len > len) {
-		__pskb_trim(skb, len);
-		if (skb->ip_summed == CHECKSUM_HW)
-			skb->ip_summed = CHECKSUM_NONE;
-	}
+	pskb_trim_rcsum(skb, len);
 
 	nf_bridge_put(skb->nf_bridge);
 	if (!nf_bridge_alloc(skb))

net/ipv6/netfilter/nf_conntrack_reasm.c

@@ -456,13 +456,9 @@ static int nf_ct_frag6_queue(struct nf_ct_frag6_queue *fq, struct sk_buff *skb,
 		DEBUGP("queue: message is too short.\n");
 		goto err;
 	}
-	if (end-offset < skb->len) {
-		if (pskb_trim(skb, end - offset)) {
-			DEBUGP("Can't trim\n");
-			goto err;
-		}
-		if (skb->ip_summed != CHECKSUM_UNNECESSARY)
-			skb->ip_summed = CHECKSUM_NONE;
+	if (pskb_trim_rcsum(skb, end - offset)) {
+		DEBUGP("Can't trim\n");
+		goto err;
 	}
 
 	/* Find out which fragments are in front and at the back of us